Accuracy of Underwater Counts of Juvenile Chinook Salmon, Coho Salmon, and Steelhead

1992 ◽  
Vol 12 (3) ◽  
pp. 598-603 ◽  
Author(s):  
T. W. Hillman ◽  
J. W. Mullan ◽  
J. S. Griffith
Keyword(s):  
Chinook Salmon ◽  
Coho Salmon ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

The Ecology of Juvenile Salmon in the Northeast Pacific Ocean: Regional Comparisons

2007 ◽  
Keyword(s):  
Continental Shelf ◽  
Chinook Salmon ◽  
Coho Salmon ◽  
Growing Season ◽  
Juvenile Salmon ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook ◽  
And Storage ◽  
Summer Growth ◽  
Storage Energy

Abstract.—Size-selective mortality combined with longer winters at high-latitudes is expected to exert strong directional selection on size, growth, and energy use and storage capacity in northern fish populations. Here, we tested the hypotheses that juvenile Pacific salmon <em>Oncorhynchus </em>spp. grow faster, reach larger size, and accumulate higher energy reserves in the marine environment at northern latitudes using juvenile Chinook salmon <em>O. tshawystcha </em>and coho salmon <em>O. kisutch </em>collected on the continental shelf from the California coast to the Bering Sea. Size reached at the end of the growing season, the quantity of energy stored prior to the onset of winter, and summer growth of juvenile Chinook and coho salmon during their first year at sea varied significantly among regions of the continental shelf. Latitudinal trends were detected for the fall size of subyearling and yearling Chinook salmon and storage energy in yearling Chinook salmon. However, they were opposite to expectations, with values decreasing from southern to northern areas. Latitudinal trends were also apparent for summer growth in juvenile yearling Chinook salmon. However, in contrast to fall size and storage energy, higher growth rates were generally observed in northern rather than in southern regions. Similarly, summer growth generally decreased from northern to southern regions in juvenile coho salmon. Storage energy did not exhibit a consistent trend with latitude in juvenile subyearling Chinook salmon and coho salmon. The different response of juvenile Chinook salmon and coho salmon to a latitudinal cline in temperature and the length of the growing season suggest that both species utilize the marine environment differently. We suggest that regional variations in juvenile salmon growth and energy accumulation may result from differences in prey quality (i.e., lipids), diet, and interspecific competition for prey resources.

Effect of Changes in Streamflow on the Microhabitat Use and Movements of Sympatric Juvenile Coho Salmon (Oncorhynchus kisutch) and Chinook Salmon (O. tshawytscha) in a Natural Stream

1994 ◽  
Vol 51 (7) ◽  
pp. 1644-1652 ◽  
Author(s):  
C. S. Shirvell
Keyword(s):  
Chinook Salmon ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Microhabitat Use ◽  
Net Energy ◽  
Optimal Position ◽  
Juvenile Chinook Salmon ◽  
Natural Stream ◽  
Juvenile Chinook ◽  
Seasonal Streamflow

The microhabitats at positions selected by juvenile coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) following a change in streamflow differed from microhabitats occupied at normal streamflows. At drought streamflow (37% mean seasonal streamflow (MSF)), juvenile coho salmon selected slower, darker, and higher sites above the streambed (P < 0.05) than sites selected at normal (75% MSF) or flood (159% MSF) flows. Juvenile chinook salmon microhabitat use changed similarly with changes in streamflow, but the differences were not significant. Up to one fifth of the fish chose positions with faster water velocities than those available either 30 cm above or 30 cm lateral to them. These fish chose positions inconsistent with the hypothesis of optimal position selection based on maximizing net energy gain. On average, fish moved 6.8 m following a change in streamflow. Juvenile coho salmon generally moved upstream in response to decreasing streamflows and downstream in response to increasing streamflows. Juvenile chinook salmon tended to move offshore and downstream in response to all streamflow changes. These results show that juvenile coho and chinook salmon will move to find suitable microhabitat following a change in streamflow and that the microhabitats are not the same at all streamflows.

Do chemically contaminated river estuaries in Puget Sound (Washington, USA) affect the survival rate of hatchery-reared Chinook salmon?

2014 ◽  
Vol 71 (1) ◽  
pp. 162-180 ◽  
Author(s):  
James P. Meador
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Coho Salmon ◽  
Life Stage ◽  
Puget Sound ◽  
Adult Life ◽  
Parallel Analysis ◽  
Differential Survival ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

This study examined the rate of survival for hatchery-reared, ocean-type juvenile Chinook salmon (Oncorhynchus tshawytscha) to the adult life stage in relation to contamination status for estuaries where they temporarily reside. The hypothesis tested here is that juvenile Chinook from Puget Sound (Washington, USA) area hatcheries exhibit differential survival as categorized by the state of contamination in their respective natal estuaries. Data were examined from 20 hatcheries that released fish to 14 local estuaries in the Greater Puget Sound area over 37 years (1972–2008). A parallel analysis was also conducted for coho salmon (Oncorhynchus kisutch) outmigrating from many of the same hatcheries. For all years combined, juvenile Chinook transiting contaminated estuaries exhibited an overall rate of survival that was 45% lower than that for Chinook moving through uncontaminated estuaries, which was confirmed when tested year by year. The results for coho originating from the same hatcheries and sharing a similar marine distribution indicated no substantial differences among estuaries. These observations have important implications for wild juvenile Chinook that spend more time in the estuary compared with hatchery-reared fish.

The Use of 17 α-methyltestosterone for Promoting Weight Increases in Juvenile Pacific Salmon

1973 ◽  
Vol 30 (8) ◽  
pp. 1099-1104 ◽  
Author(s):  
J. R. McBride ◽  
U. H. M. Fagerlund
Keyword(s):  
Weight Gain ◽  
Chinook Salmon ◽  
Structural Changes ◽  
Coho Salmon ◽  
Condition Factor ◽  
Pacific Salmon ◽  
Juvenile Chinook Salmon ◽  
Test Fish ◽  
Juvenile Pacific Salmon ◽  
Juvenile Chinook

The effect of 17 α-methyltestosterone feeding on the weight of juvenile coho salmon (Oncorhynchus kisutch) and on the weight, length, and condition factor of juvenile chinook salmon (O. tshawytscha) was determined. Significant increases in weight and length but not in condition factor were noted at all levels of steroid tested. Coho fed rations containing 10 mg/kg of the steroid for 42 days showed a 29% net weight gain and chinooks fed 1 mg/kg of the hormone for 84 days exhibited a 17% net weight gain over the respective control groups.A marked thickening of the skin was noted in the coho retained on diets containing 10 and 50 mg/kg of the steroid. This alteration was most evident in those fish fed the highest concentrations of hormone for the longest period.In the coho, diets containing 10 or 50 mg/kg of the hormone evoked marked degenerative changes in the testes. Less drastic alterations were noted in the testes of the chinooks retained on the 1 mg/kg test ration for 84 days. No apparent structural changes were noted in the ovary of any of the test fish.

Fine-scale taxonomic and temporal variability in the energy density of invertebrate prey of juvenile Chinook salmon Oncorhynchus tshawytscha

2020 ◽  
Vol 655 ◽  
pp. 185-198
Author(s):  
J Weil ◽  
WDP Duguid ◽  
F Juanes
Keyword(s):  
Energy Density ◽  
Chinook Salmon ◽  
Temporal Variability ◽  
Energy Content ◽  
Single Point ◽  
Single Species ◽  
Fine Scale ◽  
Temporal Differences ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

Variation in the energy content of prey can drive the diet choice, growth and ultimate survival of consumers. In Pacific salmon species, obtaining sufficient energy for rapid growth during early marine residence is hypothesized to reduce the risk of size-selective mortality. In order to determine the energetic benefit of feeding choices for individuals, accurate estimates of energy density (ED) across prey groups are required. Frequently, a single species is assumed to be representative of a larger taxonomic group or related species. Further, single-point estimates are often assumed to be representative of a group across seasons, despite temporal variability. To test the validity of these practices, we sampled zooplankton prey of juvenile Chinook salmon to investigate fine-scale taxonomic and temporal differences in ED. Using a recently developed model to estimate the ED of organisms using percent ash-free dry weight, we compared energy content of several groups that are typically grouped together in growth studies. Decapod megalopae were more energy rich than zoeae and showed family-level variability in ED. Amphipods showed significant species-level variability in ED. Temporal differences were observed, but patterns were not consistent among groups. Bioenergetic model simulations showed that growth rate of juvenile Chinook salmon was almost identical when prey ED values were calculated on a fine scale or on a taxon-averaged coarse scale. However, single-species representative calculations of prey ED yielded highly variable output in growth depending on the representative species used. These results suggest that the latter approach may yield significantly biased results.

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